Cloning and functional characterization of a Caenorhabditis elegans muscarinic acetylcholine receptor

A cDNA clone encoding a muscarinic acetylcholine receptor (mAChR) has been isolated from the nematode Caenorhabditis elegans. The nematode mAChR, consisted of 585 amino acids, displays a high degree of amino acid sequence homology to other invertebrate and vertebrate mAChRs. Excluding a highly variable middle portion of the third intracellular loop, the C. elegans mAChR shares about 51% amino acid sequence identity with a Drosophila mAChR and 42-44% identity with human m1-m5 mAChR subtypes. Comparison of the cDNA sequence with the corresponding genomic sequence reveals that the C. elegans mAChR gene contains ten introns, eight of them in the coding region. Pharmacological profiles of the C. elegans mAChR expressed in Chinese hamster ovary (CHO) cells were shown to be similar to those of mammalian counterparts, indicating that ligand binding domains of the receptor have been conserved during evolution. When this cloned receptor was expressed in Xenopus oocytes, acetylcholine evoked a transient Cl- current. Furthermore, activation of the receptor with oxotremorine, acetylcholine or carbachol resulted in the stimulation of phosphatidylinositol metabolism in CHO cells, suggesting that the receptor is coupled to phospholipase C activation.     

Atomically Smooth Graphene-Based Hybrid Template for the Epitaxial Growth of Organic Semiconductor Crystals

Atomically thin 2D materials are good templates to grow organic semiconductor thin films with desirable features. However, the 2D materials typically exhibit surface roughness and spatial charge inhomogeneity due to nonuniform doping, which can affect the uniform assembly of organic thin films on the 2D materials. A hybrid template is presented for preparation of highly crystalline small-molecule organic semiconductor thin film that is fabricated by transferring graphene onto a highly ordered self-assembled monolayer. This hybrid graphene template has low surface roughness and spatially uniform doping, and it yields highly crystalline fullerene thin films with grain sizes >300 nm, which is the largest reported grain size for C₆₀ thin films on 2D materials. A graphene/fullerene/pentacene phototransistor fabricated directly on the hybrid template has five times higher photoresponsivity than a phototransistor fabricated on a conventional graphene template supported by a SiO₂ wafer.     

Some physical characteristics of double-networked natural rubber

A double-networked natural rubber (DNNR) was prepared by a “two-step crosslinking” method, in which the crosslinking was achieved while the natural rubber was in a stretched condition. The swelling behavior, tensile properties, creep, recovery, and permanent set were investigated. Generally, the observed mechanical properties of DNNR, such as the Young's modulus, tensile strength, toughness, creep, recovery, and permanent set, were considerably improved as the residual extension was increased. They were, however, rather inferior to those of a single-networked natural rubber and showed a minimum at a lower residual extension of about 1.55. The degree of crosslinking and elongation at break were not greatly affected by the residual extension. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65:917–924, 1997     

Effectively reinforcing roles of the networked silica prepared using 3,3′-bis(triethoxysilylpropyl)tetrasulfide in the physical properties of SBR compounds

The networked silica having pre-fabricated networks among silica particles is a new concept for the reinforcement of rubber compounds. The networked silica was designed to improve the fuel efficiency of tires while eliminating the disadvantages such as precure and ethanol production that arise in the conventional reinforcing system using coupling reagents. The networked silica was prepared using bis(triethoxysilylpropyl)tetrasulfide (TESPT) as a connecting chemical at various loading levels. The styrene–butadiene rubber (SBR) compounds reinforced with the networked silica exhibited low filler–filler interaction and high rubber–filler interaction due to the entanglements between the rubber molecules and the connecting chains of the networked silica. The increased physical interaction improved the elastic properties and wear resistance, while lowering the rolling resistance of the rubber compounds, resulting in long tire service life and high automobile fuel efficiency. The enhanced physical properties of the SBR compounds reinforced with the networked silica supported their promising potential as reinforcing fillers for tire manufacture. The networked silica can readily replace the conventional silica-reinforced system, without requiring major modification of the processing conditions.     

Effect of Peel Angle Upon Peel Force

Measurements of peel force P per unit width are reported for samples of three adhesive tapes, adhering to two different substrates. In all cases, the work of detachment per unit area of bonded interface was found to depend upon the angle θ of detachment, increasing as θ increases. This effect is attributed to dissipation of energy in bending the tape away from the substrate at the line of detachment, to a greater degree as θ increases. Extrapolation to θ = 0 is suggested as a simple way of minimizing contributions to the observed work of detachment that arise from bending an imperfectly-elastic adhering layer as it is peeled away from a flat rigid substrate. But at small peel angles the tape tends to stretch appreciably. Peeling at 45° is recommended to minimize both effects.     

A new class of noninactivating K+ channels from aplysia capable of contributing to the resting potential and firing patterns of neurons

From the nervous system of Aplysia, we have cloned a new class of noninactivating K+ channels (aKv5.1) that are activated at low voltage and are capable of contributing to the resting potential and firing patterns of neurons. Expression of aKv5.1 in Aplysia neuron R15 revealed that aKv5.1 exerts an unusual control over cell excitability; it increased the resting potential by more than 20 mV and abolished the spontaneous bursting activity of the cell. In its ability to suppress the endogenous rhythm of R15, aKv5.1 differs in its actions from transient, inactivating K+ channels such as aKv1.1a, an Aplysia homolog of Shaker. aKv1.1a shortens the duration of the spike and increases the afterpotential, but does not suppress bursting. Thus, by expressing different classes of K+ channels, it is possible to redesign, in specific ways, the signaling capabilities of specific, identified neurons.     

Highly Stretchable,High‐Mobility,Free‐Standing All‐Organic Transistors Modulated by Solid‐State Elastomer Electrolytes

Highly stretchable, high‐mobility, and free‐standing coplanar‐type all‐organic transistors based on deformable solid‐state elastomer electrolytes are demonstrated using ionic thermoplastic polyurethane (i‐TPU), thereby showing high reliability under mechanical stimuli as well as low‐voltage operation. Unlike conventional ionic dielectrics, the i‐TPU electrolyte prepared herein has remarkable characteristics, i.e., a large specific capacitance of 5.5 µF cm^?2, despite the low weight ratio (20 wt%) of the ionic liquid, high transparency, and even stretchability. These i‐TPU‐based organic transistors exhibit a mobility as high as 7.9 cm² V^?1 s^?1, high bendability (R_c, radius of curvature: 7.2 mm), and good stretchability (60% tensile strain). Moreover, they are suitable for low‐voltage operation (V_DS = ?1.0 V, V_GS = ?2.5 V). In addition, the electrical characteristics such as mobility, on‐current, and threshold voltage are maintained even in the concave and convex bending state (bending tensile strain of ≈3.4%), respectively. Finally, free‐standing, fully stretchable, and semi‐transparent coplanar‐type all‐organic transistors can be fabricated by introducing a poly(3,4‐ethylenedioxythiophene):polystyrene sulfonic acid layer as source/drain and gate electrodes, thus achieving low‐voltage operation (V_DS = ?1.5 V, V_GS = ?2.5 V) and an even higher mobility of up to 17.8 cm² V^?1 s^?1. Moreover, these devices withstand stretching up to 80% tensile strain.     

Preparation of novel fillers,named networked silicas,and their effects of reinforcement on rubber compounds

BACKGROUND: A new concept for reinforcing silica, named networked silica, was used to achieve enhanced reinforcing performance of silica and to eliminate the disadvantage of ethanol production and precure through coupling reagents in the preparation of silica‐reinforced SBR compounds. RESULTS: The networked silicas were prepared by connecting silica particles with amine and glycidoxy groups, which had been previously coupled on their surface. The networked silicas compounded in SBR showed a significant enhancement of tensile strength accompanied with a moderate increase in modulus at a high loading of 70 phr even without using any coupling reagents. Their high performance is discussed in relation to their physical and chemical properties investigated using thermogravimetry, infrared spectroscopy, ζ‐potential, transmission electron microscopy and nitrogen adsorption methods. CONCLUSION: The improved reinforcing performance of networked silicas confirmed their feasibility as reinforcing materials for the manufacture of highly stable tires. The high tensile strength achieved using the networked silicas is probably due to the physical entanglements of rubber molecules with the networks formed among silica particles. Copyright © 2008 Society of Chemical Industry     

Improvement of the tool life of a micro-end mill using nano-sized SiC/Ni electroplating method

High mechanical properties of a tungsten carbide micro-end-mill tool was achieved by extending its tool life by electroplating nano-sized SiC particles (< 100 nm) that had a hardness similar to diamond in a nickel-based material. The co-electroplating method on the surface of the micro-end-mill tool was applied using SiC particles and Ni particles. Organic additives (saccharin and ammonium chloride) were added in a Watts bath to improve the nickel matrix density in the electroplating bath and to smooth the surface of the co-electroplating. The morphology of the coated nano-sized SiC particles and the composition were measured using Scanning Electron Microscope and Energy Dispersive Spectrometer. As the Ni/SiC co-electroplating layer was applied, the hardness and friction coefficient improved by 50%. Nano-sized SiC particles with 7 wt% were deposited on the surface of the micro-end mill while the Ni matrix was smoothed by adding organic additives. The tool life of the Ni/SiC co-electroplating coating on the micro-end mill was at least 25% longer than that of the existing micro-end mills without Ni/SiC co-electroplating. Thus, nano-sized SiC/Ni coating by electroplating significantly improves the mechanical properties of tungsten carbide micro-end mills.